I'm too sleepy to search now but it's here. Someone has done the reverse drum replacement and replaced the clutch packs while he was at it too. I think it was a father and son team if I'm not mixing up DIYs in my head this late. If you find it, he had links to the parts for the rebuild.
Regardless of what the transmission chart says verify it physically. You could get lucky and could have gotten the GM. In which case it's just a solenoid.